Methods to achieve bistability in specified materials, for instance PCT application No. US2010/001105 discloses magnetite nanoparticles within a solid media. Through a combination of magnetic or electrical tuning and a UV reversible curing process, structures can be fixed by converting the liquid medium to a solid, which can be converted from a solid back to a liquid to change the color of the medium with the colloidal particles.
In addition, a number of inventions relating to tuning apparatuses designed to modulate frequencies of a bistable materials and/or solutions are known, including the cathode ray tube (CRT). For example, the CRT uses high-powered electromagnets to power and steer a stream of electrons, causing them to hit the television screen and make it glow.
The use of alternating magnetic fields using magnetic particles was first introduced by Gilchrist et al. (1957) to produce intratumoral heating. The tissue heating comes from magnetic friction from the magnetic particles. Advances in the field of alternating magnetic field heating of magnetic nanoparticles induced by magnetic friction, have been extensive in the last 50 years. There is an array of scientific and technological application of this phenomenon, in particular, biomedicine. Recently, superparamagnetic have been used for inducing hyperthermia in cancerous tumors. A host of different magnetic and superparamagnetic particles and nanoparticles have been identified in the literature.
Typical magnetic field amplitudes are small of order 150 Oe and frequencies are high for example 300 kHz. By using a magnet to heat superparamagnetic particles in a medium, the heating of the medium can be controlled by particle concentration, magnetic amplitude and the frequency of oscillating the magnetic field. References: Gilchrist Ric, Medal R Shorey S D et al. Ann Surgery 1957: 146:596; Jordan A Schulz R, Wust P., et al. J. Magnetism Magnetic Mater. 1999: 201:413; and DeNardo G L and DeMardo S J Cancer Biotherapy and Radiopharm. 200: 23:671
However, it would be desirable to provide a tuning apparatus designed to manipulate colloidal particles in a bistable medium to create color change and/or color design by means of applying an external magnetic or electrical field(s), electromagnetism, an electrical frequency, light, and/or pressure to the bistable material.